In this study we focus on the misclassification of issue reports regarding software performance in OSS development. IEEE Std 610 [1] defines performance as “The degree to which a system or component accomplishes its designated functions within given constraints, such as speed, accuracy, or memory usage.” The definition implies that there is no rigorous criteria nor quantitative measure to detect a software performance problem, but rather it relies on a subjective judgement. OSS users sometimes mistakenly report a performance bug as a request for improving software performance and sometimes mistakenly report an improvement request for fixing a performance bug. The misclassification of report types can impedes the efficient bug-fix process in OSS development, since OSS developers preferentially spend time fixing bugs which might be improvement requests (i.e., not bugs) in reality. In this paper we strengthen our previous study for the Apache Wicket project by manually inspecting 1,000 bugs and 1,000 improvement requests respectively to more precisely understand the impacts of the misclassification on the bug-fix process in OSS development.